Method and apparatus for forming fabrics and fabrics made by the method

ABSTRACT

A method for forming a material having an individually stabilized ply includes providing a ply having a non-orthogonal orientation. A stabilizing agent is then applied to maintain the orientation of the ply. The stabilizing agent could alternately be applied before forming the ply. The ply may be woven in a non-orthogonal orientation, or may have its orientation changed to the final non-orthogonal orientation. Changing may occur over multiple steps and may include using an accumulator and/or payout station to change the orientation.

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit under 35 U.S.C. § 11 9(e)from co-pending U.S. Provisional Patent Application Serial No.60/466,762, filed 04/30/2003, incorporated herein by,reference in itsentirety.

BACKGROUND OF THE INVENTION

[0002] Some woven materials are advantageously made by having fill yarnsthat are not orthogonal to the warp yarns. For instance, material usedto make covers for radar antennas, other radar systems, and other typesof antennas. These covers may be referred to as “radome covers.” Radomecovers may be as large as 80 to 1 68 feet or larger in diameter and canbe mounted on a platform or foundation where they are subject to highwind speeds. In some locations, a cover must be capable of withstandingwind speeds up to 200 mph. Because of their size and the possibly highwind speeds, the covers are often exposed to high stresses in alldirections along its surface. The covers must also, in manycircumstances, be capable of withstanding the effects of harshenvironmental conditions (sun, heavy rain, ice, blowing sand,temperature extremes, high winds, etc.). To accomplish this, the covermay be constructed of multiple layers (plies) having yarns running indifferent directions. This may be accomplished by taking two plies, eachhaving an orthogonal orientation, and stitching or otherwise bonding thetwo plies together such that the warp yarns of a first ply are at a 45degree angle from the warp yarns of a second ply.

[0003] These covers are used to protect various antennas. For instance,they are typically used to cover weather radar antennas, airsurveillance radar antennas, satellite communication station antennas,and other antenna.

[0004] Industrial belts are another woven material based product thatmay advantageously be made by having fill yarns that are not orthogonalto the warp yarns. These belts are often subject to high stresses due toexcess applied tension (required to prevent slippage of the conveyorbelt on the machine drive rolls), stretching, heavy loads conveyed bythe belt, and high speed movement combined with side to side movementinduced by guiding systems or off-tracking problems. Applied tension,thermal extremes and thermal shock, often cause belt distortion (e.g.longitudinal ridges). In addition, tracking problems can occur due touneven warp yarn tension.

[0005] Expansion joints are used to span the distance between rigidductwork, connecting for example, a metal flue duct with a metal orsolid emissions stack in a power plant (the various pipes, ducts, andother conduits herein referred to as “conduits” unless stated otherwisein a claim). The expansion joint compensates for and accommodatesdimensional changes associated with the expansion and contraction of theductwork, as it is exposed to thermal cycling. It acts like a bellows asthe solid ductwork expands and contracts as it transitions throughheating and cooling cycles. The expansion joint must accommodatestresses, intermittent flexing and environmental conditions (high winds,temperature excursions, sunlight, caustic flue gasses) associated withthe application.

[0006] Many designs for these applications are limited by currenttechnology in making the individual plies. Individual plies can beoriented such that the angle of the fill yarns with respect to the warpyarns is changed. If not purposefully stabilized, yarns that arenon-orthogonal tend to revert to an orthogonal pattern. Thus, ifhandled, these oriented plies tend to lose their preferred orientation.Further, current methods of holding an oriented ply in place oftenrequire that the oriented ply be held by tacking, stitching, or bondingit to some other article. This requirement limits the ability to designcustom fabrics which have the best combination of properly constructedplies for a particular application. Further, these techniques areawkward and difficult in terms of manufacturing. It would be preferableto have a system that allows individual plies to be manufactured, wherethe individual plies are able to maintain their orientation. It wouldalso be preferable to have a multi-ply material where each plycontributes a unique contribution to the overall composition; a materialwhere each ply can have its own geometric configuration of the yarns,its own matrix material, and its own resin content.

[0007] Under current processes used to make non-orthogonal fabrics, aprocess is used wherein the fabric must be handled between the time inwhich the orientation of the fabric is made non-orthogonal and the timeat which the non-orthogonal orientation is set. During this time period,the fabric may tend to revert to an orthogonal orientation. It would bedesirable to have a continuous process for setting a non-orthogonalorientation of a fabric that shortens the time period in which thefabric may tend to revert to an orthogonal orientation. If a continuousprocess will not be used, it would be desirable to be able to bettermaintain the non-orthogonal orientation in the time period between whenthe orientation of the fabric is made non-orthogonal and the time whenthe non-orthogonal orientation is set.

[0008] The fabrics of many of these materials are desirably coated. Thiscoating can-have the purpose of-resisting environmental elements,maintaining physical properties (including strength and interplyadhesions), or of otherwise making the woven fabric more functional.When plies that have been fixed together (to hold their orientation)before coating, it is difficult to create a multi-ply material with goodwet out during the coating process. Poor wet out leads to internal voidsand surface defects (blisters, bubbles, and craters) in thecoating—possibly from air trying to escape the voids during the coatingprocess.

[0009] The teachings herein below extend to those embodiments which fallwithin the scope of the appended claims, regardless of whether theyaccomplish one or more of the above-mentioned needs.

SUMMARY OF THE INVENTION

[0010] One embodiment is directed to a ply of woven material in whichthe orientation of the fill yarns are non-orthogonal to the warp yarns.The material further comprises a polymer coating, which stabilizes thenon-orthogonal orientation of the yarns.

[0011] Another embodiment is directed to a multi-ply woven material. Thematerial includes a first ply having fill yarns orthogonal to its warpyarns, and a second ply having fill yarns that are not orthogonal to itswarp yarns. At least the second ply of the material is individuallystabilized.

[0012] Another embodiment is directed to a multi-ply woven material. Thematerial includes a first ply having fill yarns and warp yarns, and asecond ply having fill yarns that are not orthogonal to its warp yarns.At least the second ply of the material is individually coated.

[0013] Another embodiment is directed to a multi-ply composite. Thecomposite comprises a first ply and a second ply, the second ply havinga non-orthogonal orientation. The second ply is woven and isindividually stabilized.

[0014] Another embodiment is directed to a composite. The compositecomprises a woven ply having a non-orthogonal orientation. The woven plyis individually stabilized by a matrix material selected from the groupconsisting of silicone rubber, urethane rubber, polyvinyl chloride,polyvinylidene chloride, polyvinyl alcohol, fluoropolymers, urethane,polyurethane, and combinations thereof.

[0015] Another embodiment is directed to a flexible composite. Theflexible composite comprises a woven ply having a non-orthogonalorientation. The woven ply of the flexible composite is individuallystabilized.

[0016] Another embodiment is directed to a multi-ply material. Themulti-ply material includes a first woven ply, a second woven ply, and athird woven ply fixedly coupled to the first and second plies. At leastone ply of the multi-ply material has fill yarns that are not orthogonalto its warp yarns, and each ply has an about equal resin content.

[0017] Another embodiment is directed to a multi-ply material. Themulti-ply material includes three plies. The middle ply is fixedlycoupled to the other two plies and has a resin content at least as highas both of the outer plies. The middle ply has a non-orthogonalorientation. Another embodiment is directed to a flexible multi-plymaterial. The flexible multi-ply material comprises a first ply and asecond ply. The first ply and the second ply are not coupled to eachother by stitching. The plies may be laminated to each other. Anotherembodiment is directed to a flexible multiply composite. The flexiblemulti-ply composite comprises a first ply, a second ply, and a thirdply. At least one of the first ply, second ply, and third ply comprisesa non-orthogonal orientation. In some embodiments, at least two of thefirst ply, second ply, and third ply comprise non-orthogonalorientations. Each of the three plies may comprise woven plies. Theflexible multi-ply material may comprise a fourth ply.

[0018] Another embodiment is directed to a structure comprised of afabric as disclosed in the previous paragraphs. The structure maycomprise a radome comprising a flexible radome cover, a machinecomprising a belt, a building comprising a flexible roof and/or askylight, a piping system comprising a flexible expansion joint, and aboat comprising sails.

[0019] Another embodiment is directed to a radome. The radome includes amulti-ply material configured to cover an antenna. The multiply materialcomprises a first ply having fill yarns and warp yarns, and a second plyhaving fill yarns that are not orthogonal to the warp yarns. At leastthe second ply of the multi-layer material is individually coated.

[0020] Another embodiment is directed to a wireless signal-basedstructure. The structure includes an antenna, and a cover. The coverincludes a multi-ply material having a first ply having fill yarns andwarp yarns, and a second ply having fill yarns that are not orthogonalto its warp yarns. At least the second ply of the cover is individuallycoated.

[0021] Another embodiment is directed to a radome cover. The radomecover comprises a woven ply, the ply comprising a first set of yarns anda second set of yarns. The first set of yarns and second set of yarnsare arranged such that the ply has a non-orthogonal orientation.

[0022] Another embodiment is directed to a radome cover. The radomecover comprises a multi-ply material comprising a first woven ply havingfill yarns and warp yarns, the first ply having a negative orientation;and a second woven ply coupled to the first ply and having fill yarnsand warp yarns, the second ply having a positive orientation.

[0023] Another embodiment is directed to a radome cover. The radomecover comprises a woven ply, the ply comprising a first set of yarns anda second set of yarns arranged such that the ply has a non-orthogonalorientation. The ply of the radome cover is individually stabilized.

[0024] Another embodiment is directed to a radome cover. The radomecover comprises a first ply and a second ply. The radome cover has atrapezoidal tear strength of at least about 300 lbs. The trapezoidaltear strength may be measured in a warp, fill, or diagonal direction.The radome cover may have a trapezoidal tear strength of at least about400 or at least about 600 lbs. The radome cover may have two or moretrapezoidal tear strengths of at least about 300 lbs (e.g. warp, fill,first diagonal, and/or second diagonal).

[0025] Another embodiment is directed to a radome cover. The radomecover comprises a first ply, a second ply, and a third ply. The radomecover may comprise a fourth ply. One of the plies of the radome maycomprise a non-orthogonal orientation. Each of the plies may comprisewoven plies.

[0026] Another embodiment is directed to a radome comprising a radomecover configured according to any of the embodiments disclosed above.

[0027] Another embodiment is directed to a system comprising an antennaand a radome, a radome cover of the radome being configured according toany of the embodiments discussed above.

[0028] Another embodiment is directed to an industrial belt. The beltincludes a multi-ply material configured to carry a load. The multi-plymaterial has a first ply having fill yarns and warp yarns, and a secondply having fill yarns that are not orthogonal to the warp yarns. Atleast the second ply of the multi-ply material is individually coated.Further, the multi-ply material is configured to form a loop.

[0029] Another embodiment is directed to a machine having a belt withgreater dimensional stability. The machine includes a belt comprising amulti-ply material. The multi-ply material includes a first ply havingfill yarns and warp yarns, and a second ply, the second ply having fillyarns that are not orthogonal to the warp yarns. The second ply isindividually stabilized. The machine further includes a drivingmechanism coupled to the belt such that the driving mechanism causes thebelt to move.

[0030] Another embodiment is directed to a composite to be formed into abelt. The fabric comprises a woven ply, the ply comprising a first setof yarns and a second set of yarns. The first set of yarns and secondset of yarns are arranged in a non-orthogonal orientation.

[0031] Another embodiment is directed to a composite to be formed into abelt. The composite comprises a woven ply, the ply comprising a firstset of yarns and a second set of yarns arranged such that the ply has anon-orthogonal orientation. The ply of the belt is individuallystabilized.

[0032] Another embodiment is directed to a composite to be formed as abelt. The composite comprises a multi-ply material comprising a firstwoven ply having fill yarns and warp yarns, the first ply having anegative orientation; and a second woven ply coupled to the first plyand having fill yarns and warp yarns, the second ply having a positiveorientation.

[0033] Another embodiment is directed to a belt formed from a compositeconstructed according to any of the embodiments discussed above. Thebelt may comprise an open weave belt.

[0034] Another embodiment is directed to a machine comprising rollersand having a belt constructed according to any of the embodimentsdiscussed above stretched between the rollers.

[0035] Another embodiment is directed to a machine comprising a drivingmechanism and having a belt constructed according to any of theembodiments discussed above coupled to the driving mechanism such thatthe driving mechanism can be operated to cause the belt to move.

[0036] Another embodiment is directed to a method of using a beltaccording to any of the embodiments discussed above. The methodcomprises carrying packages weighing more than 60 pounds using the belt.

[0037] Another embodiment is directed to a method of using a beltaccording to any of the embodiments discussed above. The methodcomprises drying articles using the belt.

[0038] Another embodiment is directed to an architectural fabric. Thearchitectural fabric comprises a first woven ply; and a second wovenply. The first woven ply and the second woven ply of the architecturalfabric are integrally coupled.

[0039] Another embodiment is directed to an architectural fabric. Thearchitectural fabric comprises a woven ply, the ply comprising a firstset of yarns and a second set of yarns. The first set of yarns and thesecond set of yarns are arranged such that the ply has a non-orthogonalorientation.

[0040] Another embodiment is directed to an architectural fabric. Thearchitectural fabric comprises a woven ply, the ply comprising a firstset of yarns and a second set of yarns arranged in a non-orthogonalorientation. The ply of the architectural fabric is individuallystabilized.

[0041] Another embodiment is directed to a roof comprising anarchitectural fabric constructed according to any of the embodimentsdiscussed above.

[0042] Another embodiment is directed to a structure comprising anarchitectural fabric constructed according to any of the embodimentsdiscussed above.

[0043] Another embodiment is directed to a structure including a roof,the roof comprising an architectural fabric constructed according to anyof the embodiments discussed above.

[0044] Another embodiment is directed to a fabric expansion joint. Theexpansion joint comprises a woven ply, the ply comprising a first set ofyarns and a second set of yarns. The first set of yarns and second setof yarns are arranged in a non-orthogonal orientation.

[0045] Another embodiment is directed to a fabric expansion joint. Theexpansion joint comprises a ply, the ply comprising a first set of yarnsand a second set of yarns arranged in a non-orthogonal orientation. Theply of the expansion joint is individually stabilized.

[0046] Another embodiment is directed to an assembly. The assemblycomprises a first conduit, a second conduit, and an expansion jointextending between the first conduit and the second conduit. Theexpansion joint may be constructed according to any of the embodimentsdiscussed above. The first and second conduits may be rigid and may havea fixed position.

[0047] Another embodiment is directed to a system for forming anindividually stabilized ply. The system comprises an accumulatorconfigured to receive a woven fabric ply; and a means for individuallystabilizing a non-orthogonal orientation of the woven fabric ply afterit has been accumulated by the accumulator. The ply may be individuallystabilized by coating, laminating, or by some other method. Anorientation of the ply may be changed by one of an accumulator and apayout station (which may include changing the orientation using both anaccumulator and a payout station).

[0048] Another embodiment is directed to a system for forming anindividually stabilized ply. The system comprises a means for alteringan orientation of a woven fabric ply; and a means for individuallystabilizing the altered orientation of the woven fabric ply.

[0049] Another embodiment is directed to a method of forming a wovenmaterial. The method includes inputting a material having warp yarns andfill yarns, changing the angle of the fill yarns with respect to thewarp yarns, such that the warp yarns and fill yarns are non-orthogonal,and coating the material at about the time.

[0050] Another embodiment is directed to a method. The method comprisescoating a material having yarns at an angle to each other, and changingthe angle of the yarns with respect to each other in the coatedmaterial.

[0051] Another embodiment is directed to a method for forming a wovenmaterial. The method comprises forming a single ply of material havingyarns at an angle with respect to each other, changing an angle of theyarns with respect to each other at a time, and coating the single plyof material at about the same time.

[0052] Another embodiment is directed to a method for forming anindividually stabilized ply. The method includes weaving a ply having afirst orientation; changing the orientation of the ply that has beenwoven; and individually stabilizing the changed orientation of the ply.

[0053] Another embodiment is directed to a method for stabilizing a ply.The method comprises forming a ply having a non-orthogonal orientation;and coating the ply in its non-orthogonal orientation to individuallystabilize the ply.

[0054] Another embodiment is directed to a method for stabilizing a ply.The method comprises forming a ply having a non-orthogonal orientation;and laminating the ply in its non-orthogonal orientation to individuallystabilize the ply.

[0055] Another embodiment is directed to a method for forming anindividually stabilized ply. The method comprises weaving a ply;maintaining the woven ply in a non-orthogonal orientation for anextended period before the ply is individually stabilized; andindividually stabilizing the ply that has been maintained in itsnon-orthogonal orientation.

[0056] A number of methods and products are directed to woven materials.These methods could also be used to form more knitted materials (andother fabrics). Further, even though some embodiments are directed tocoating of the fabrics, these fabrics could also be laminated, or gothrough some other process for applying a stabilizing compound.

[0057] Other principle features, advantages, and variations fallingwithin the scope of the invention will become apparent to those skilledin the art upon review of the following drawings, the detaileddescription, and the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0058]FIGS. 1A and 1B are diagrams showing woven materials with warp andfill yarns at orthogonal and non-orthogonal angles;

[0059]FIG. 2 is a layer diagram illustrating a multi-layered materialhaving layers which can be individually coated;

[0060]FIG. 3A is a flow diagram of a method for forming flexiblecomposites having at least one ply with a non-orthogonal orientation;

[0061]FIG. 3B is a flow diagram for a method for forming single layermaterials which can maintain a non-orthognal warp yarn—fill yarnrelationship (orientation) without being fixed to another layer prior tostabilization of the orientation;

[0062]FIG. 3C is a flow diagram for a method for forming multi-layermaterials from various preformed plies;

[0063]FIG. 3D is a flow diagram of a method for forming a radome from amulti-layer material having at least one ply having a non-orthogonalorientation;

[0064]FIG. 3E is a flow diagram of a method of using a belt comprisingat least one ply having a non-orthogonal orientation;

[0065]FIGS. 4A to 4C are one illustration of a system that can be usedto carry out the method described in FIG. 3B;

[0066]FIG. 5A is an antenna based system according to one embodiment;

[0067]FIG. 5B is a radome according to one embodiment;

[0068]FIG. 5C is a layer diagram of a multi-layer material for use as aradome according to one embodiment;

[0069]FIG. 6A is a machine having a fabric based belt according to oneembodiment;

[0070]FIG. 6B is a layer diagram of a multi-layer material for use as anindustrial belt according to one embodiment;

[0071]FIG. 7A is a cross-sectional side view of a structure having aroof made of a multi-layer material according to one embodiment;

[0072]FIG. 7B is a plan view of the structure shown in FIG. 7A;

[0073]FIG. 7C is a layer diagram of a multi-layer material for use as astructural material according to one embodiment; and

[0074]FIG. 8A is an industrial system incorporating an expansion jointaccording to one embodiment; and

[0075]FIG. 8B is a layer diagram of a multi-layer material that may beused to form an expansion joint according to one embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0076] Referring to FIGS. 1A and 1B, an orthogonal ply of woven material6 includes fill yarns 12 that are orthogonal to warp yarns 10. Anon-orthogonal ply of woven material 8, on the other hand, has fillyarns 12 that are not orthogonal to warp yarns 10. Non-orthogonal pliescan be characterized by the skew angle (α) between warp yarns 10 andfill yarns 12 and the direction in which fill yarns 12 run (from left toright). Skew angle (α) is defined by the smallest angle (0°<α<90° forplies with a non-orthogonal orientation) between warp yarns 10 and fillyarns 12. Material 8 is at about a 45° angle and has fill yarns thatrise. A material 8 that has fill yarns that rise is typically referredto as having a positive skew angle, having an Z orientation, and/orhaving a right-hand orientation.

[0077] The fact that fill yarns 12 rise is typically inconsequentialsince a single ply of material 8 is generally symmetrical, and, whencoated as an individual ply, can be flipped over to have fill yarns 12that fall. In a multi-layer material, orientation may be determined withrespect to some reference. For instance, in a radome, orientation isdetermined with reference to an observer who is on the inside of theradome. The same may be true when using the multi-layer material in anarchitectural and/or expansion joint application.

[0078] Reference to orientation of a ply is a reference of theorientation of a first set of yarns of the ply (e.g. fill yarns) withrespect to a second set of yarns that are non-parallel to the first set(e.g. warp yarns). Unless stated otherwise, “orientation” of a ply isgenerally a reference to the skew angle of the yarns of the ply.

[0079] Reference to a shape/geometry of a ply or a multi-layer materialshall mean the three-dimensional form of the ply and/or the material.

[0080] Skew angle shall be a reference to the angle formed between oneset of yarns (e.g. warp yarns) and a second set of yarns (e.g. fillyarns) if the ply were placed as a flat (generally two-dimensional)sheet. Sets of yarns that are parallel would have a 0 degree skew angleand sets of yarns that are orthogonal would have a 90 degree skew angle.In a woven material, skew angle generally refers to the angle formed bythe warp yarns and fill yarns.

[0081] A matrix material is generally a different material than thefibers/yarns which it holds in place. While matrix materials arediscussed herein with respect to some embodiments, any place that theterm matrix material is used in the description of the figures, thedescription could alternately use the terms stabilizing agent or bondingagent.

[0082] Fabric as used herein shall refer to a textile structure producedby interlacing yarns, fibers, or filaments. Fabric tends to initially besubstantially planar, but the fabric may tend to curl, or otherwisedeform from a planar shape due to the orientation of the layer(s) usedto make the fabric. A fabric with a non-planar shape is contemplated bythis application.

[0083] A fabric according to this application tends to be formed byweaving and/or knitting. Fabric having woven and/or knitted plies shallbe referred to as an intertwined fabric or an intertwined ply. Weavingas used herein is not limited to joining two yarns made of similarmaterials.

[0084] A coated fabric as used herein shall refer to any fabric to whicha substance such as a lacquer, plastic, resin, rubber, or varnish hasbeen applied in firmly adhering layers to provide certain properties,such as stabilization of the orientation of the fabric.

[0085] Reference to a non-orthogonal orientation of a ply is a referenceto a non-orthogonal orientation of at least a whole section of the ply,and not merely a reference to the orientation of the ply at certainpoints (such as at the fringes of the ply). Further, reference to anon-orthogonal orientation is generally a reference to a ply having askew of of more than about 5 and less than about 85. These limits areset to differentiate between manufacturing deviations that occur inorthogonal plies, and plies that actually have a non-orthogonalorientation as the term is meant to be used herein.

[0086] Referring to FIG. 2, a multi-layer material 100 has a firstorthogonal layer 102 (alpha≈90°), a first non-orthogonal layer 104(alpha≈45°), a second non-orthogonal layer 106 (alpha≈30°), a secondorthogonal layer 108 (alpha≈90°), and a third non-orthogonal layer 110(alpha≈45°). While not common in a large number of embodiments, it isconceivable that a single ply may have multiple orientations. In mostembodiments, a single ply will have substantially the same orientationthroughout the ply (i.e. there may be minor deviations in theorientation—for instance, at the fringes of the ply—but the ply generalhas a constant orientation throughout the ply).

[0087] The individual layers can be individually designed andindividually coated. When the layers are individually coated, each layercan have its own yarn material and matrix material, and its own yarn.geometry and resin content. Further, layer 110 may have itsnon-orthogonal yarn orientation maintained by individually coating layer110, while layers 104 and 106 (or some other layers) have theirnon-orthogonal yarn orientation maintained by use of stitching.

[0088] Multi-layer material 100 may be designed to be a flexiblecomposite. Examples of applications that may employ flexible compositesinclude radome covers (especially air-supported radome covers), belts,roofing, skylights, and other architectural fabrics, and fabric-basedexpansion joints. Multi-layer material 100 may comprise at least threeplies. In other embodiments, multi-layer material 100 may comprise atleast four plies; These plies may be woven plies. One or more of theseplies may have a non-orthogonal orientation, which orientation may beindividually stabilized for that ply.

[0089] Layers 102 to 110 can be held together by any number of means.For instance, they can be powder bonded, laminated, stitched, etc. Also,even if the individual layers are coated, multi-layer material 100 canhave an additional coating applied after any combination of layers 102to 110 have been combined.

[0090] Multiple advantages can be achieved by forming multi-layermaterials from individually coated/stabilized plies. For instance,non-orthogonal plies made by conventional methods are not coated untilafter two or more plies have been stitched or otherwise bonded together.When these materials are coated, the resulting material tends to havelarger numbers of surface defects and void spaces. Multi-layer materialsmade by individually coating a single ply, on the other hand, tend tohave fewer void spaces and fewer surface defects.

[0091] Also, multi-layer materials made by individually coating singleplies can lead to unique arrangements. For instance, a middle layer canhave a higher resin content (amount of resin per square yard ) than itstwo adjacent layers. Also, different resin types can be used foradjoining layers.

[0092] Individual plies according to some embodiments may have a skewangle that is no less than about 30 degrees or 40 degrees. Individualplies according to some embodiments may have a skew angle that is nomore than about 60 degrees or 50 degrees. These embodiments may be inany shape, including, but not limited to, radome covers, belts,architectural fabrics, and expansion joints.

[0093] According to some embodiments of a multi-ply material, themulti-ply material will comprise a first ply having a positiveorientation and a second ply having a negative orientation. According tomost of these embodiments, the two opposing orientations occur inoverlapping sections of the two plies. Again, these embodiments may bein any shape, including, but not limited to, radome covers, belts,architectural fabrics, and expansion joints. According to someembodiments, one or more of the plies will have a substantially closed(non-porous) structure. Further, the composite as a whole may have asubstantially closed structure. The substantially closed structure maybe a result of a tight weave of the yarns. According to otherembodiments, the composite may have an open structure such as an openweave structure.

[0094] Referring to FIG. 3A, a method for creating a multi-layer fabricfor a particular application includes creating a stabilized ply ofmaterial at block 230, using the stabilized ply (typically inconjunction with other plies) to form a multi-layer fabric suitable forthe application at block 240, and then applying the material to theapplication at block 250.

[0095] Referring to FIG. 3B, a method for forming a stabilized ply atblock 230 may include forming the material at block 200. The materialcould be formed by any number of conventional weaving or knittingprocedures. The material could also be formed by any other procedurethat can create a material with one set of yarns at an angle to anotherset of yarns. Some yarns that may be used to form the plies includefiberglass, nylon, polyester, aramid (such as Kevlar® or Nomex®available from Dupont), polyethylene, polyolefins, polyimides, carbon,polybenzimidazole (PBI), polybenzoxazole (PBO), and/or fluorocarbon.Further, other materials may be used to form the yarns of a ply. A yarnmay be formed from one of these materials or may comprise a combinationof these materials (potentially twisted together).

[0096] In a ply having Warp yarns and fill yarns, the warp yarns and thefill yarns may have different compositions than each other. Further, thewarp yarns may be a uniform composition (i.e. all warp yarns are made ofabout the same materials) or may have a non-uniform composition (i.e.some warp yarns have a different composition than other warp yarns).Further still, the fill yarns may have a uniform composition or may havea non-uniform composition.

[0097] An optional matrix material can be applied to the formed materialat block 202 prior to changing the angle of the yarns. The matrixmaterial could be any number of materials applied in any number ofmanners. For example, the matrix material could be a silicone rubber,urethane rubber, a urethane, a polyurethane, polyvinyl chloride,polyvinylidene chloride, polyvinyl alcohol, and their copolymers withacrylic acid or acrylic acid esters or other vinyl ester monomers,fluoropolymers, including fluoroplastics (such as PTFE, FEP, TFA, ETFE,THV, etc.) and fluoroelastomers, some other polymeric material, orblends thereof. Typical fluoropolymer matrix materials may includemonomers of chlorotrifluoroethylene (CTFE) and vinylidene fluoride(VF2), either as homopolymers, or as copolymers with TFE, HFP, PPVE,PMVE and ethylene or propylene. Additionally, the fluropolymer matrixmaterial could comprise a perfluoropolymer such as homopolymers andcopolymers of tetrafluoroethylene (TFE), hexafluoropropylene (HFP) andfluorovinyl ethers, including perfluoropropyl and perfluoromethyl vinylether. Other materials may also be used as the matrix material. Theapplied material could alternatively be some other type of stabilizingagent.

[0098] The matrix material could be applied by coating the formedmaterial, laminating the formed material, powder bonding the formedmaterial, being sprayed onto the formed material, etc.

[0099] The matrix material is preferably impregnated into the yarns withminimal encapsulation; the goal being to add some stability to the shapeof the formed material, while at the same time allowing a change in theshape of the material to be carried out.

[0100] After block 202, the angle of the fill yarns with respect to thewarp yarns is changed at block 204. Since most materials are formed intheir orthogonal state, changing the angle typically involves making thematerial become non-orthogonal. Also, changing the angle typicallyinvolves changing the angle throughout the material. For instance, asection of the material (a section being defined by one point along thewarp yarns to another point along the warp yarns) where all of the fillyarns are substantially orthogonal to the warp yarns would change to asection where all of the fill yarns are substantially non-orthogonal tothe warp yarns (while ideally all of the yarns would face the exact samedirection, there will inevitably be some minor deviations from thedesired angle on occasion, especially near the edges).

[0101] Additionally, changing the angle at block 204 may be carried outin more than one step. For instance, a 45° angle may be too severe anangle to form in one step, so the 45° angle can be formed first as a 30°angle and then the 30° angle is converted to a 45° angle.

[0102] Once the angle has been set at block 204, the single ply materialis then stabilized at block 206. This process typically occurs at orabout the same time as the angle is formed (e.g. within about a minuteor less depending on the speed with which the material is moved throughthe production line). This typically reduces the amount of deviationfrom the desired angle, because the non-orthogonal yarns would have lessof a chance to revert to an orthogonal pattern.

[0103] Alternately, a technique may be used to maintain the changedorientation of the fabric. The fabric may then be transported from thedevice used to change the orientation and coated at a later point intime. One such technique for maintaining a non-orthogonal orientation ofan individual ply is an interleaf technique. If used, the technique usedto maintain the non-orthogonal orientation of the ply can preferably beable to maintain the orientation for extended periods of time (e.g. morethan one day).

[0104] The material used as a stabilizer at block 206 can be the sameas, or can be different from, that used as the optional impregnatingmaterial added at block 202. The same list of materials discussed abovewith respect to block 202 may be used at block 206. The stabilizing atblock 206 preferably more firmly sets the angle of the material,although, while it can be held firmly and rigidly in place, theorientation of the ply need not be locked in place or made entirelyrigid. Material that has been stabilized at block 206 can preferablyhold its shape, in its individual layer form, for extended periods oftime.

[0105] Here, a material is considered “stabilized” even if no physicalfixing to another substance has taken place, so long as a substance (thestabilizing agent) introduced to the formed material greatly increasesthe resistance of a non-orthogonal material to deviate from itspreferred, non-orthogonal orientation.

[0106] A ply which has such a stable orientation that it will not tendto easily revert to some other orientation may be considered stabilized.A ply which achieves this stabilization before being joined withadditional plies may be considered individually stabilized. Anindividual ply which achieves this individual stabilization by theintroduction of a matrix material may be referred to as a ply that isindividually stabilized by a matrix material.

[0107] This individual stabilization is a particularly useful propertyfor a non-orthogonally orientated ply to have, although not allembodiments of non-orthogonally oriented plies according to the claimedsubject matter need be individually stabilized. Reference to anon-orthogonal ply in a claim does not imply that the ply isindividually stabilized unless expressly stated in the claim.

[0108] Referring to FIG. 3C, a method for forming the material at block240 may include combining the individual plies which have beenstabilized in place at block 230 to form a multi-layer material at block208. The multi-layer material can further be formed using uncoatedlayers, multi-layer materials not having individually coated layers,non-fabric layers (such as protective coatings), etc.

[0109] Additional matrix material may be applied to the multi-layermaterial at block 210. Also, other coatings and laminations can be addedto the multi-layer material to affect the properties of the material.

[0110] The material is then shaped at block 212. Some typical shapes forthe material depend on the use of the multi-layer material. Forinstance, when used as radomes, the material is typically formed intopieces that can be combined to form a truncated sphere. When used as anindustrial belt, the material is typically left in a rectangular shape,which then is connected at its ends. Also, other substances, such asinductive elements can be added to the material.

[0111] Once the multi-layer material is in its formed shape at block212, further coatings and laminations can be applied to the multi-layermaterial to hold the orientation, and/or to give it other desiredproperties.

[0112] Referring to FIG. 3D, in one embodiment an article having anindividually stabilized ply with a non-orthogonal orientation may beapplied at block 250 to an air-supported radome. In a radome having sucha stabilized ply, a base ring may be set around the base of the antennaat block 214. The base ring may have a plurality of clamps and may beprepared with an adhesive secured gasket and/or anti-seizing spray.

[0113] The radome fabric is then placed over the antenna at block 216.The radome fabric may be lifted over the antenna using a crane.Depending on the construction of the radome, this step may be betteraccomplished if wind speeds are not high.

[0114] The radome fabric is then connected to the base ring at block 218this may be done by way of the clamps on the base ring. Once this isaccomplished, an air-supported radome may be inflated (e.g. usingblowers).

[0115] Referring to FIG. 3E, a belt comprising an individuallystabilized ply may be attached to an apparatus at block 220. An articlemay then be placed on the belt at block 222. The article may be a heavyarticle and may have a weight of at least about 40 or 60 pounds. If theapparatus at block 220 is part of a system for drying articles, the beltmay be used to dry the article at block 224. Using a belt to dry or curean article may include using the belt to convey the article through azone of increased temperature often in conjunction with a cooling zone.The belt is thus subject to both thermal extremes and thermal cycling.

[0116] Referring to FIG. 4A, an embodiment of an apparatus for formingplies of material with a non-orthogonal orientation includes a payoutstation 320 which pays out fabric to an accumulator 330. Fabric fromaccumulator 330 passes through dip pan 340 where fabric 306 is coatedwith matrix material. Fabric from dip pan 340 passes between meteringbars 346 and goes through tower 350. Tower 350 may be used to dry, bake,sinter, and/or cure the matrix material onto the fabric. After passingthrough tower 350, the fabric is taken up by take-up 360.

[0117] Payout station 320 may be used to skew fabric 306. Referring toFIG. 4B, payout station 320 includes a roll 322 carrying material with astarting orientation. The material is fed from roll 322 to capstanrollers 324. Roll 322 may be set at an angle 326 from rollers 324. Whenangle 326 is non-zero, the tension between roll 322 and rollers 324 maycause fabric 306 to change its orientation. Angle 326 is generallyplaced between zero and forty-five degrees.

[0118] Accumulator 330 may also be used to skew fabric 306. Referring toFIG. 4C, accumulator 330 includes upper accumulator rolls 334 and loweraccumulator rolls 332. If upper rolls 334 and lower rolls 332 are placedat a non-zero angle 336 with respect to each other, then tension betweenrolls 334 and rolls 332 may cause fabric 306 to change its orientation.Here, upper rolls 334 are shown as the rolls which are adjusted toadjust angle 336. In other embodiments, lower rolls 332 are adjusted orboth upper rolls 334 and lower rolls 332 are adjusted. This process maybe repeated within the accumulator for each of the sets of rollers.Angle 336 may be set to be between zero and fifteen degrees, or may beset equal to zero or fifteen degrees.

[0119] In some embodiments payout station 320 is used to change theorientation of fabric 306. In other embodiments, accumulator 330 is usedto change the orientation of fabric 306. In either of these embodiments,a combination of payout station 320 and accumulator 330 may be used tochange the orientation of fabric 306.

[0120] Capstans 324, 342, and 362 may be used to adjust the amount oftension provided to fabric 306. Also, the distance between metering bars346 may be used to control the thickness of an applied coating. Further,the shape of metering bars 346 may be used to control the surfacetexture of fabric 306. For instance, a metering bar 346 may includenotches to form ribs on fabric 306, and may move from side to side toform the ribs in a non-linear pattern.

[0121] Instead of using a dip coating apparatus, some other coatingapparatus may be used to coat fabric 306.

[0122] Radomes

[0123] Referring to FIGS. 5A and 5B, an assembly 400 includes an antenna402 supported on a tower 404. Antenna 402 is covered by radome 406 whichis also supported on tower 404. Antenna 402 could alternately be locatedon a building, could be ground-based, etc.

[0124] Radome 406 is configured to protect antenna 402 from the elementswithout causing significant interference to the signals to betransmitted and received by antenna 402. Radome 406 may be configured tohave good performance at high frequencies and/or good performance atmultiple frequencies. Radome 406 would preferably have low transmissive,absorptive, and/or reflective loss of signal at high/multiplefrequencies. A lack of significant interference may indicate that theradome cover contributes to a signal loss of no more than about 0.5% ofthe signal strength from the signal source at at least one andpotentially at multiple frequencies. Good performance may indicate thatthe radome cover contributes to a signal loss of no more than about0.05% at one or more frequencies.

[0125] Antenna 402 may be a high frequency radar antenna. Antenna 402could be a phased array or a dish (such as a parabolic dish, a splitcylinder dish) and may be rotating or non-rotating. Radomes 406 are usedas part of a number of different types of radar system assemblies. Forexample, radomes 406 can be used in conjunction with weather radarsystems, and airport radar systems.

[0126] Instead of using a radar antenna, assembly 400 could includeother antennas 402, one such antenna being a satellite communicationantenna. One example of an assembly 400 using a satellite communicationantenna is a ground terminal for the US Air Force unmanned aircraft.

[0127] Radome 406 primarily includes a multi-layer material 430.Multi-layer material 430 is typically between about 0.04 and 0.1 inchthick, although other thickness are possible. In some embodiments,multi-layer material 430 may be less than 0.04 inches or may be as thickas 0.3 inches. In one embodiment,-multi-layer material 430 is about 0.07to 0.09 inches thick.

[0128] In some embodiments, multi-layer material 430 may have a warptrapezoidal tear strength of at least about 300 lbs, or may be selectedto have a warp trapezoidal tear strength of at least about 450 lbs. Inanother embodiment, multi-layer material 430 may be selected to have awarp trapezoidal tear strength of at least about 650 lbs.

[0129] In some embodiments, multi-layer material 430 may have a filltrapezoidal tear strength of at least about 300 lbs, or may be selectedto have a fill trapezoidal tear strength of at least about 450 lbs. Inanother embodiment, multi-layer material 436 may be selected to have afill trapezoidal tear strength of at least about 650 lbs.

[0130] In some embodiments, multi-layer material 430 may have atrapezoidal tear strength at a first diagonal of at least about 300 lbs,or may be selected to have a diagonal trapezoidal tear strength of atleast about 450 lbs. In another embodiment, multi-layer material 430 maybe selected to have a diagonal trapezoidal tear strength of at leastabout 650 lbs. In some of these embodiments, multi-layer material 430may have a trapezoidal tear strength at a second diagonal of at leastabout 300 lbs, or may be selected to have a second diagonal trapezoidaltear strength of at least about 450 lbs. In another of theseembodiments, multi-layer material 430 may be selected to have a seconddiagonal trapezoidal tear strength of at least about 650 lbs.

[0131] In some embodiments, multi-layer material 430 may have a weightof at least about 65 osy or may be selected to have a weight of at leastabout 75 osy. In some embodiments, multi-layer 430 material may beselected to have a weight of less than about 100 osy or may be selectedto have a weight less than about 90 osy.

[0132] In some embodiments, multi-layer material 430 may have a warpstrip tensile strength of at least about 1300 lbs./in. or may beselected to have a warp strip tensile strength of at least about 1600lbs./in. In one embodiment, multi-layer material 436 may be selected tohave a warp strip tensile strength of no more than about 1900 lbs./in.

[0133] In some embodiments, multi-layer material 430 may have a fillstrip tensile strength of at least about 1300 lbs./in. or may beselected to have a fill strip tensile strength of at least about 1600lbs./in. In one embodiment, multi-layer material 430 may be selected tohave a fill strip tensile strength of no more than about 1900 lbs./in.

[0134] In some embodiments, multi-layer material 430 may have a warptensile strength after a 50 pound creasefold of at least about 1200lbs./in. or may be selected to have a warp tensile strength after a 50pound creasefold of at least about 1650 lbs./in. In some embodiments,multi-layer material 430 may have a warp tensile strength after a 50pound creasefold of no more than about 2000 lbs./in., or may be selectedto have a warp tensile strength after a 50 pound creasefold of no morethan about 1900 lbs./in.

[0135] In some embodiments, multi-layer material 430 may have a filltensile strength after a 50 pound creasefold of at least about 1200lbs./in. or may be selected to have a fill tensile strength after a 50pound creasefold of at least about 1650 lbs./in. In some embodiments,multi-layer material 430 may have a fill tensile strength after a 50pound creasefold of no more than about 2000 lbs./in., or may be selectedto have a fill tensile strength after a 50 pound creasefold of no morethan about 1900 lbs./in.

[0136] According to one embodiment, a foam layer 432 may be added tomulti-layer material 430. Foam layer 432 primarily serves as a layer ofinsulation for antenna 402. Foam layer 432 may also serve to providestructural support to radome 406. As illustrated in FIG. 5B, radome 406may also include structural support elements 434 integrally connectingportions of radome 406, which are used as supports for the structure ofradome 406.

[0137] While not limited to such radomes, the fabrics described in thepresent application may have a greater contribution to radome coversthat rely on multi-layer material 430 to provide the primary structuralsupport for the radome cover. These radomes may be radomes that do notinclude foam layer 432 and/or secondary structural support elements 434.

[0138] One example of a radome in which multi-layer fabric 430 may serveas a primary structural member responsible for bearing loads is anair-supported radome. An air-supported radome may rely on a differencein air-pressure (e.g. a higher air pressure inside the radome) tosupport the radome instead of relying solely on structural supportelements 434. Typical air-supported radomes 406 may be configured to notinclude secondary structural support elements 434 at all. Anair-supported radome 406 may also lack foam layer 432.

[0139] An air-supported radome may include a blower pressurizationsystem configured to maintain the increased air pressure. In oneembodiment, the blower pressurization system comprises a three-stageblower pressurization system. The blower pressurization system mayinclude a blower such as a 230/460 VAC, 3 phase, 60 Hz power blower, mayinclude one or more anemometers, an external pressure tap, and an airintake assembly. An air-supported radome 406 may also include agalvanized steel base ring assembly, and a lifting ring. Radome 406 mayalso include airlock door assemblies, a lightning rod assembly, andcirculation fans.

[0140] Some objectives for selecting characteristics of a multi-plymaterial used to form a radome include providing high tensile strengthin multiple directions (such as three or four directions), retainingtensile strength in the multiple directions after handling and flexing,balanced elongation/modulus in the multiple directions, inter-plyintegrity, flexibility, ability to pattern, fabricate, and cut thematerial, and the ability to both be RF transmissive with a low loss ofsignal strength and/or accuracy and not sustain negative side effectsfrom RF transmission—such as overheating—(e.g. choosing materials withlow amounts of interaction with the signal(s) at their intendedfrequency or frequencies).

[0141] A primary consideration for meeting the objectives is theselection of an appropriate yarn material. The properties of thematerial from which the yarns are made can have a significant affect onthe tensile strength of the radome, the retained tensile strength of thematerial, the flexibility of the radome, resistance to environmentalelements, balance of modulus and elongation, and other of the objectiveslisted above. For instance synthetic fibers, especially an aramid suchas Kevlar, may provide sufficient flexibility and retention of tensilestrength for use in radome applications. Matrix materials can also beselected for specific characteristics. Typically, fluoroploymers areselected to withstand temperature requirements, provide sufficient RFtransmissivity and to provide protection from the elements (rain, sun,etc).

[0142] Also, the use of orthogonal and non-orthogonal plies should be aprimary design consideration. When non-orthogonal plies are used, thesize and direction of the oriented yarns may affect how the loads areshared. A proper choice of orientation, angle and direction, couldresult in a more even distribution of load sharing between yarns, andmay result in more even load sharing in multiple directions. Further,non-orthogonal layers may be combined having one layer with a positiveangle and another layer with a negative angle to achieve better results.Also, the selection of the orientation of individual plies of themulti-ply material may affect the overall tensile strength of the radomein the various directions.

[0143] Other considerations that may affect these properties include theprocessing history (such as thermal cycling), use of twisted yarns,crimp balance, and choice of which yarns will bear structural loads.

[0144] Yarns bearing structural loads will typically be thicker thanyarns that are not intended to bear structural loads. Reference to anon-structural yarn does not mean that when placed in the field the yarnwill not be subjected to and bear some loads, but rather, that it isnot. intended to be a primary bearer of the load.

[0145] Structural yarns may be placed in even increments around thefabric (i.e. the structural yarns may be located every certain angleamount such as every 30 degrees, every 45 degrees, every 60 degrees,etc.). Alternatively, the structural yarns may be placed in unevenincrements around the fabric (i.e. not at regularly spaced intervals).

[0146] The number of directions in which structural yarns extend in amulti-layer material may be used to differentiate the multi-layermaterial. For instance, a material having structural yarns in twodirections may be referred to as bi-axial, three directions istri-axial, etc. An orthogonal ply with structural warp and fill yarnswould be considered to be bi-axial. A multi-layer material having twoorthogonal plies where the warp yarns of one ply are rotated 45 degreesfrom the warp yarns of the other ply, and where the warp and fill yarnsof each ply contain structural yarns would be considered to be aquadri-axial material. Radome covers and flexible composites accordingto some embodiments would comprise multi-axial materials.

[0147] Referring to FIG. 5C, one exemplary embodiment of a multi-layermaterial 430 which may be useful in a radome application comprises aplurality of plies 462-466 which are coupled to each other. Plies462-466 may be joined by stitching the plies together, laminating theplies together, powder bonding the plies together, and/or may be joinedby some other method. The plies may be directly connected, or they maybe indirectly connected by intervening materials.

[0148] Multi-layer material 460 may include a protective film 461 on asurface 468 of multi-layer material 460 which is facing the environment.Multi-layer material 460 may also have a protective film (not shown)located on an interior face 470. Further still, multi-layer material 460may only have a film on interior face 470.

[0149] Protective film 461 may be designed to block UV light and may bedesigned to protect plies 462-466 from the penetration of environmentalelements (such as water, sand/dirt, and others).

[0150] One or more of plies 462-466 may be individually stabilizedand/or have a non-orthogonal orientation. Further, one of plies 462-466may have a negative orientation and another may have a positiveorientation.

[0151] Also, additional plies may be added to multi-layer material 460or illustrated plies may be removed from multi-layer material 460. Insome embodiments, multi-layer material 460 may be composed essentiallyof about two to about six plies.

[0152] Plies 426-466 may comprise yarns of any of the materialsdescribed with respect to block 200 (FIG. 3B). Typical yarns used toform radomes include aramids (such as Kevlar), fiberglass, and/orpolyester. The plies 462-466 may have warp yarns made of one materialand fill yarns made of another material. Further, the yarns may comprisemore than one type of material. Further still, each of plies 462-466 mayhave its own unique set of yarns.

[0153] Exemplary matrix materials for plies 462-466 include any of thematrix materials described above with respect to block 202 (FIG. 3B). Atypical matrix material used to form a radome includes PTFE.

[0154] Multi-layer material 460 may be a flexible composite of theindividual plies and matrix materials.

[0155] Other properties and characteristics of plies used in theconstruction of multi-layer materials used as radome covers can bedetermined with reference to FIGS. 1 to 4C above. Methods of formingradome covers may be seen with respect to FIGS. 3A to 3D above.

[0156] Belts

[0157] Referring to FIGS. 6A and 6B, an industrial machine 500 has abelt 502 and a driving mechanism 504. The driving mechanism 504 includesrollers 506, 508 which are coupled to motor 510. Belt 502 is stretchedacross rollers 506, 508 and may be placed under tension. If tension isapplied to belt 502, the tension may result in deformation of the belt.

[0158] The belt may also tend to be deformed by the use of automatictracking systems used to keep the belt aligned on the equipment. Furtherstill, the belt may tend to be deformed by an uneven placement of loadson the belt.

[0159] These forces may be applied at angles that are not parallel orperpendicular to the direction of travel of the belt, and may not beadequately compensated for by the use of orthogonal plies with yarnsrunning in a direction parallel to the intended direction of travel ofthe belt.

[0160] Multi-layer material 530 of belt 502 is preferably configured toresist shape deformation due to the tension, thermal cycling, thermalextremes and side to side stress to which it is subjected, and therebyretain better dimensional stability.

[0161] To compensate for these forces, the belt fabric may include plieswith yarns which are non-perpendicular and non-parallel to thelongitudinal direction of the belt. One example of such a ply would be anon-orthogonal ply with warp yarns that are perpendicular to thedirection of travel of the belt (e.g. having fill yarns that arenon-perpendicular and non-parallel to the longitudinal direction of thebelt). A non-orthagonal construction may tend to more uniformitydistribute and deflect loads, thereby mitigating or preventing sometracking problems.

[0162] Dimensional stability can be increased by specifically designingbelts to resist deformation. One manner of doing this is designing abelt with layers having warp and fill yarns at different angles. Thelayers may also be made having different coatings. Using individuallycoated layers allows greater ability to design a belt with optimalproperties, including increased dimensional stability.

[0163] Dimensional stability may be an issue for belts having an openweave since the warp yarns and fill yarns are not as densely packed.Such open weave belts are commonly classified as controlled porositybelts or open mesh belts. Controlled porosity belts tend to have a totalamount of open area of greater than 0% and less than about 15%, and haveporosities of about 5 to 50 SCFM. The current design may be more usefulwhen directed to controlled porosity belts having a more open design,such as about 5% to about 15% open area. Open mesh belts, on the otherhand, tend to have a total amount of open area greater than 10%,typically having an open area in the range of 10% to about 80%. In someembodiments, such open mesh belts will have a total amount of open areathat is no less than about 30%. Also, in some embodiments, such openmesh belts will have a total amount of open area that is no more thanabout 60%.

[0164] Open weave designs including only orthogonal plies may tend todeform (narrow, ridge, and/or fold over) when pulled at certain anglesor when exposed to thermal cycling. The addition of skewed plies addsstrength at angles where orthogonal plies do not add strength, therebyimproving the dimensional stability of the belt at those angles.

[0165] In one embodiment, the multi-layer material of the presentapplication is not a closed porosity belt (e.g. does not have a totalopen area of about 0%).

[0166] Belt 502 may comprise a multi-layer material 520. Such amulti-layer material 520 may include plies that have warp yarns whichare non-orthogonal to fill yarns. Use of such skewed plies may causebelt 502 to curl, ridge, or fold over. To counter the tendency to curl,ridge, or fold over, one or more orthogonal plies may be included inbelt 502, preferably as the outer layers.

[0167] Open weave belts with improved dimensional stability may beuseful in applications such as drying applications.

[0168] When designing a belt, it is advantageous to choose plies withproperties which contribute to the dimensional stability, flex fatigueresistance, inter-ply adhesion, tear strength, tracking, beltelongation, thermal cycling, and use temperature of the belt. Theorientation of the plies of the fabric of the belt primarily contributesto the dimensional stability of the belt.

[0169] Referring to FIG. 6B, one exemplary embodiment of a multi-layermaterial 520 which may be useful in a belt application comprises aplurality of plies 522-528 which are coupled to each other. Plies522-528 may be joined by stitching the plies together, laminating theplies together, powder bonding the plies together, or may be joined bysome other method. The plies may be directly connected, or they may beindirectly connected together by intervening materials.

[0170] One or more of plies 522-528 may be individually stabilizedand/or have a non-orthogonal orientation. Further, one of plies 522-528may have a negative orientation and another may have a positiveorientation.

[0171] Multi-layer material 520 may include a protective film (notshown) on a face 550 of multi-layer material 520. Multi-layer material520 may also have a protective film (not shown) located on a face 552 ofmulti-layer material 520 opposite from face 550. Further still,multi-layer material 520 may only have a film on face 552.

[0172] Also, additional plies may be added to multi-layer material 520or illustrated plies may be removed from multi-layer material 520. Insome embodiments, multi-layer material 520 may be composed essentiallyof about three to about six plies.

[0173] Additionally, multi-layer material 520 may include flights (notshown) integral with multi-layer material 520. Flights may include ribs,cleats, ridges, lugs, or other protuberances. The flights may be locatedon either or both of surfaces 550 and 552. The flights may be continuousor discontinuous. The flights may be located transverse to the directionof travel of the belt (e.g. to prevent items from slipping) or mayextend parallel to the direction of the belt (e.g. to prevent the beltfrom weaving from side to side). If flights are on both faces ofmulti-layer material 520, the flights may extend in the same direction(such as for use in contact toasters) or may extend in differentdirections (e.g. parallel flights on the bottom face of the belt toprevent weaving and transverse flights on the top of the belt to preventslippage).

[0174] Plies 522-528 may comprise yarns of any of the materialsdescribed with respect to block 200 (FIG. 3B). The type of yarn that iscommonly used for a particular belt depends on the application for whichthe belt is being used. For example, a belt designed to be used in ahigh temperature application may include yarns comprising fiberglass, anaramid such as Kevlar or Nomex®, some other high temperature yarn, oryarns comprised of combinations of these materials. As another example,open mesh belts used in drying applications commonly include yarnscomprised of fiberglass/Nomex®, Glass/Kevlar®, Nomex®/Kevlar® orcombinations thereof. The plies 522-528 may have warp yarns made of onematerial and fill yarns made of another material. Further, the yarns maybe comprised of combinations of materials. Further still, each of plies522-528 may have its own unique set of yarns.

[0175] Exemplary matrix materials for plies 522-528 include any of thematrix materials described above with respect to block 202 (FIG. 3B).Again, the type of matrix material that is commonly used for aparticular belt depends on the application for which the belt is beingused. For example, a belt designed to be used in a high temperatureapplication where a low coefficient of friction is needed may use amatrix material comprising a fluoropolymer such as PTFE or some othermaterial meeting these standards. As another example, open mesh beltsused in drying applications commonly include matrix materials comprisingsilicone rubber and/or PTFE. A belt for use in a high temperaturecooking application may comprise a silicone rubber matrix material.

[0176] Multi-layer material 520 may be a flexible composite of theindividual plies and matrix materials.

[0177] Other properties and characteristics of plies used in theconstruction of multi-layer materials used as belts can be determinedwith reference to FIGS. 1 to 4C above. One method of using a beltaccording to one embodiment may be seen with respect to FIG. 3E above.

[0178] Architectural Fabrics

[0179] Referring to FIGS. 7A-7C, a structure 600 includes walls 601, 602and roof 604. Roof 604 includes support beams 606 and a multi-layermaterial 608 which is supported by support beams 606. Alternatively,roof 604 could include some type of support mechanism other than supportbeams 606 such as cabling and/or air pressure. Multi-layer material 608is preferably designed to allow light to shine through, but not allowother environmental elements, such as dust and water, to pass through.Some examples of structures 600 that use a high performance fabric as aroof material include sports stadiums (such as the MinneapolisMetrodome) and airports (such as Denver International Airport). Formingthe roof material from individually coated layers allows greaterflexibility when designing a roof with optimal properties.

[0180] Multi-layer material 608 is preferably designed to be at leastpartially light transmissive. The term “translucent” will be used torefer to the light transmissivity and will refer to both translucent andtransparent materials unless stated otherwise in a claim at issue. Someembodiments of multi-layer material 608 have an overall lighttransmissivity of at least about at 5. Some of these embodiments have anoverall light transmissivity of at least about 20%. Some embodimentshave an overall light transmissivity of no more than about 5%. Some ofthese embodiments have an overall light transmissivty of no more thanabout 45%.

[0181] One material which may be suitable for allowing lighttransmission is glass fibers and polyester/nylon. These materials may becoated with polytetrafluroethylene (PTFE), poly vinyl chloride (PVC)and/or liquid silicone rubber (LSR) or some other form of siliconerubber.

[0182] Architectural fabrics may be classified between permanentstructures and movable structures. While usable for both types ofstructures, multi-layer material 608 formed as disclosed in thisapplication tends to be more applicable to permanent structures. Moreparticularly, such multi-layer materials may be useful for forming roofsor skylights for permanent structures like domes and airports.

[0183] Referring to FIG. 7C, one exemplary embodiment of a multi-layermaterial 640 which may be useful in an architectural application(especially for a permanent structure) comprises a plurality of plies644-648 which are coupled to each other. Plies 644-648 may be joined bystitching the plies together, laminating the plies together, powderbonding the plies together, or may be joined by some other method. Theplies may be directly connected, or they may be indirectly connectedtogether by intervening materials.

[0184] One or more of plies 644-648 may be individually stabilizedand/or have a non-orthogonal orientation. Further, one of plies 644-648may have a negative orientation and another may have a positiveorientation.

[0185] Multi-layer material 640 may include a protective film 642 on anexternal face 660 of multi-layer material 640 facing the environment.Multi-layer material 640 may also have a protective film (not shown)located on a face 662 of multi-layer material 640 exposed to theinterior of the structure. Multi-layer material 640 generally does nothave a protective layer on interior face 662 without also having aprotective layer on external face 660 in products intended for use asroofing and skylight materials.

[0186] The protective layer 642 is generally chosen to be translucentand may be clear, tinted, or some combination of clear and tinted. Asuitable tint for a protective layer 642 of a material 640 configured tobe used as a roofing or skylight material is a blue tint. Protectivelayer 642 may be used to make multi-layer material 640 waterproof andmay be used to protect the yarns of the plies 644-648 from environmentalelements. Protective layer 642 may include pigments which may impartcolor for architectural decorative effect.

[0187] Protective layer 644 may include a fluoropolymer which mayprotect the composite from rain, aid in shedding snow more easily,and/or provide a self-cleaning surface.

[0188] Also, additional plies may be added to multi-layer material 640or illustrated plies may be removed from multi-layer material 640. Insome embodiments, multi-layer material 640 may be composedessentially-of about two to about five plies.

[0189] Plies 644-648 may comprise yarns of any of the materialsdescribed with respect to block 200 (FIG. 3B). The type of yarn that iscommonly used for architectural fabrics depends on the application inwhich the fabric is being used. For example, when the fabric is used asa roofing or skylight material of a structure (and particularly forpermanent structures), common yarn materials include polyester, nylon,Kevlar, and/or fiberglass. The plies 644-648 may have warp yarns made ofone material and fill yarns made of another material. Further, the yarnsmay be comprised of combinations of these materials. Further still, eachof plies 644-648 may have its own unique set of yarns.

[0190] Exemplary matrix materials for plies 644-648 include any of thematrix materials described above with respect to block 202 (FIG. 3B).The type of matrix material that is commonly used for architecturalfabrics depends on the application in which the fabric is being used.For example, when the fabric is used as a roofing or skylight materialof a structure (and particularly for permanent structures), commonmatrix materials include PTFE, PVC, and silicone rubber.

[0191] Multi-layer material 640 may be a flexible composite of theindividual plies and matrix materials.

[0192] Other properties and characteristics of plies used in theconstruction of multi-layer materials for use as architectural fabricscan be determined with reference to FIGS. 1 to 4C above. Methods offorming architectural fabrics may be seen with respect to FIG. 3A above.

[0193] Expansion Joints

[0194] Referring to FIG. 8A, an industrial system 700 includes a firstrigid conduit 710 coupled to a second rigid conduit 712 by an expansionjoint 714. Expansion joint 714 is connected to first conduit 710 byfirst connectors 718 (which may comprise bolts) and to second conduit712 by second connectors 719. Industrial system 700 may also includebars 716 extending between first conduit 710 and second conduit 712.Expansion joint 714 may be comprised of a multi-layer material 730 (FIG.8B).

[0195] Extending between may mean that the extending item extends fromone conduit to the other, may mean that a portion of the item extends inthe length between the two conduits, may mean that the entire extendingitem is located in a space between the conduits (whether directlyconnected or not), or may include other positions consistent with theordinary meaning of the term.

[0196] Expansion joint 714 may have a bellow-like shape. Expansion joint714 may be used to span the gap between two gas stream containments(e.g. smoke stack and power generation plant). Alternately, expansionjoint 714 may be used to fabricate chutes in a chemical plants.Expansion joint 714 could also be used for other purposes.

[0197] When designing expansion joints, it is advantageous to design amulti-layer material 730 with plies that contribute to the tensilestrength, tear strength, flex fatigue resistance, inter-ply adhesion,and use temperature of the expansion joint. The orientation of the pliesmay contribute to the ability to uniformly distribute loads as well asprevent tear migration by deflecting the direction of the stress.

[0198] Referring to FIG. 8B, one exemplary embodiment of a multi-layermaterial 730 which may be useful in an expansion joint applicationcomprises a plurality of layers 740-746 which are coupled to each other.Plies 740-744 may be joined by stitching the plies together, laminatingthe plies together, powder bonding the plies together, and/or may bejoined by some other method. The plies may be directly connected, orthey may be indirectly connected together by intervening materials.

[0199] Multi-layer material 730 may include a protective film 746 on asurface 734 of multi-layer material 730 which is facing an interior ofthe expansion joint 716. Protective film 746 may be configured toprotect the remainder of multi-layer material 730 from the articlesbeing transported through conduits 710, 712 (FIG. 8A). For instance, thematerial in the ducts of a powerplant may include fine particles (“ash”)as well as hot corrosives. Film 746 may include polytetrafluoroethylene(PTFE), or other fluropolymers films including but not limited toperfluoroalkoxy (PFA) and fluorinated ethylene- propylene (FEP). Also,in some embodiments film 746 may be selected to have a thickness that isat least about 0.002 inches and/or may be selected to have a thicknessthat is no more than about 0.1 inches.

[0200] One or more of plies 740-744 may be individually stabilized andhave a non-orthogonal orientation. Further, one or more of plies 740-744may have a negative orientation and one or more may have a positiveorientation.

[0201] Also, additional plies may be added to multi-layer material 730or illustrated plies may be removed from multi-layer material 730. Insome embodiments, multi-layer material 730 may be composed essentiallyof about two to about five plies.

[0202] Plies 740-744 may comprise yarns of any of the materialsdescribed with respect to block 200 (FIG. 3B). Typical yarns used toform expansion joints include fiberglass, Nomex® & Kevlar®. The plies740-744 may have warp yarns made of one material and fill yarns made ofanother material. Further, each of plies 740-744 may have its own uniqueset of yarns. The yarns may also be hybrid; consisting of one yarn pliedof several different fibers (e.g. glass, Nomex®, Kevlar®) in one or bothdirections.

[0203] Exemplary matrix materials for plies 740-744 include any of thematrix materials described above with respect to block 202 (FIG. 3B).Typical matrix materials used to form expansion joints include PTFE, FEP& PFA along with a fluroelastomer.

[0204] Multi-layer material 730 may be a flexible composite of theindividual plies and matrix materials.

[0205] Other properties and characteristics of plies used in theconstruction of mult-layer materials used as expansion joints can bedetermined with reference to FIGS. 1 to 4C above.

EXAMPLES

[0206] The following example is presented to illustrate the presentinvention and to assist one of ordinary skill in making and using thesame. The examples are not intended in any way to otherwise limit thescope of the invention. Layer Warp Yarn Fill Yarn Matrix StructuralNumber Material Material Material Orientation Yarns 1 Kevlar Kevlar PTFEOrthogonal Warp, Fill 2 Kevlar Kevlar PTFE −60° Fill 3 Kevlar KevlarPTFE +60° Fill

[0207] According to this exemplary embodiment, which may be useful for aradome, a multi-layer material 460 (FIG. 5C) includes a first ply 462with an orthogonal orientation, a second ply 464 with a negativeorientation, and a third ply 466 with a positive orientation. First ply462, second ply 464, and third ply 466 comprise Kevlar warp and fillyarns woven together and coated with PTFE. Second ply 464 and third ply466 have 60 degree skew angles, and have fill yarns that are structuraland warp yarns that are non-structural. When formed as multi-layermaterial 430, the warp yarns of first ply 462, second ply 464, and thirdply 466 extend in about the same (parallel) direction. Plies 462-466 arelaminated together using technology such as that disclosed in U.S. Pat.No. 5,141,800. Alternatively, plies 462-466 may be stitched togetherusing threads.

[0208] Multi-layer material 430 has a first face 468 extending towardsthe outside environment and a second face 470 facing the interior ofradome 406. The two skew plies 464, 466 are located towards interiorface 470 and the orthogonal ply 462 is located towards exterior face468.

[0209] A protective layer 461 is applied to first ply 462 as a barrierbetween the plies and the environment. Protective layer 461 may includea UV blocking film which includes PTFE, TiO2, and carbon black. One suchUV blocking film is sold by Saint-Gobain Performance Plastics under thename CHEMFILM™. Layer Warp Yarn Fill Yarn Matrix Structural NumberMaterial Material Material Orientation Yarns 1 Kevlar Kevlar PTFEOrthogonal Warp, Fill 2 Kevlar Kevlar PTFE −45° Fill 3 Kevlar KevlarPTFE +45° Fill

[0210] According to this exemplary embodiment, which may be useful for aradome, a multi-layer material 460 (FIG. 5C) includes a first ply 462with an orthogonal orientation, a second ply 464 with a negativeorientation, and a third ply 466 with a positive orientation. First ply462, second ply 464, and third ply 466 comprise Kevlar warp and fillyarns woven together and coated with PTFE. Second ply 464 and third ply466 have 45 degree skew angles, and have fill yarns that are structuraland warp yarns that are non-structural. When formed as multi-layermaterial 430, the warp yarns of first ply 462, second ply 464, and thirdply 466 extend in about the same direction. Plies 462-466 are laminatedtogether using technology such as that disclosed in U.S. Pat. No.5,141,800. Alternatively, plies 462-466 may be stitched together usingthreads.

[0211] Multi-layer material 430 has a first face 468 extending towardsthe outside environment and a second face 470 facing the interior ofradome 406. The two skew plies 464, 466 are located towards interiorface 470 and the orthogonal ply 462 is located towards exterior face468.

[0212] A protective layer 461 is applied to first ply 462 as a barrierbetween the plies and the environment. Protective layer 461 includes aUV blocking film which may include PTFE, TiO2, and carbon black. Onesuch UV blocking film is sold by Saint-Gobain Performance Plastics underthe name CHEMFILM™. Layer Warp Yarn Fill Yarn Matrix Structural NumberMaterial Material Material Orientation Yarns 1 Kevlar Kevlar PTFEOrthogonal Warp, Fill 2 Kevlar Kevlar PTFE −30° Fill 3 Kevlar KevlarPTFE +60° Fill 4 Kevlar Kevlar PTFE −60° Fill 5 Kevlar Kevlar PTFE +30°Fill

[0213] According to this exemplary embodiment, which may be useful for aradome, a multi-layer material 460 (FIG. 5C) includes a first ply 462with an orthogonal orientation, a second ply 64 and a fourth ply (notshown) with negative orientations, and a third ply 466 and a fifth ply(not shown) with positive orientations. First ply 462, second ply 464,third ply 466, the fourth ply, and the fifth ply comprise Kevlar warpand fill yarns woven together and coated with PTFE. Third ply 466 andthe fourth ply have 60 degree skew angles, and have fill yarns that arestructural and warp yarns that are non-structural. Second ply 464 andthe fifth ply have 30 degree skew angles, and have fill yarns that arestructural and warp yarns that are non-structural. When formed asmulti-layer material 430, the warp yarns of first ply 462, second ply464, third ply 466, the fourth ply and the fifth ply extend in about thesame direction. The five plies are laminated together using technologysuch as that disclosed in U.S. Pat. No. 5,141,800. Alternatively, theplies may be stitched together using threads.

[0214] Multi-layer material 430 has a first face 468 extending towardsthe outside environment and a second face 470 facing the interior ofradome 406. The two skew plies 464, 466 are located towards interiorface 470 and the orthogonal ply 462 is located towards exterior face468.

[0215] A protective layer 461 is applied to first ply 462 as a barrierbetween the plies and the environment. Protective layer 461 includes aUV blocking film which may include PTFE, TiO2, and carbon black. Onesuch UV blocking film is sold by Saint-Gobain Performance Plastics underthe name CHEMFILM™. Layer Warp Yarn Fill Yarn Matrix Structural NumberMaterial Material Material Orientation Yarns 1 Kevlar Kevlar PTFE −60°Fill, Warp 2 Kevlar Kevlar PTFE +60° Fill, Warp

[0216] According to this exemplary embodiment, which may be useful for aradome, a multi-layer material 460 (FIG. 5C) includes a first ply 462with a negative orientation, and a second ply 464 with a positiveorientation. First ply 462 and second ply 464 comprise Kevlar warp andfill yarns woven together and coated with PTFE. First ply 462 and secondply 464 have 60 degree skew angles, and have fill yarns that arestructural. Plies 462 and 464 also have warp yarns which each bear about50% of a structural load. When formed as multi-layer material 430, thewarp yarns of first ply 462 and second ply 464 extend in about the samedirection. Plies 462, 464 are laminated together using technology suchas that disclosed in U.S. Pat. No. 5,141,800. Alternatively, plies 462,464 may be stitched together using threads.

[0217] A protective layer 461 is applied to first ply 462 as a barrierbetween the plies and the environment. Protective layer 461 includes aUV blocking film which may include PTFE, TiO2, and carbon black. Onesuch UV blocking film is sold by Saint-Gobain Performance Plastics underthe name CHEMFILM™. Layer Warp Yarn Fill Yarn Matrix Structural NumberMaterial Material Material Orientation Yarns 1 Kevlar Kevlar PTFE −45°Fill, Warp 2 Kevlar Kevlar PTFE +45° Fill, Warp

[0218] According to this exemplary embodiment, which may be useful for aradome, a multi-layer material 460 (FIG. 5C) includes a first ply 462with a negative orientation, and a second ply 464 with a positiveorientation. First ply 462 and second ply 464 comprise Kevlar warp andfill yarns woven together and coated with PTFE. First ply 462 and secondply 464 have 45 degree skew angles, and have fill yarns that arestructural. Plies 462 and 464 also have warp yarns which are structuraland each bear about 50% of a structural load along a common axis. Whenformed as multi-layer material 430, the warp yarns of first ply 462 andsecond ply 464 extend in about the same direction. Plies 462, 464 arelaminated together using technology such as that disclosed in U.S. Pat.No. 5,141,800. Alternatively, plies 462, 464 may be stitched togetherusing threads.

[0219] A protective layer 461 is applied to first ply 462 as a barrierbetween the plies and the environment. Protective layer 461 includes aUV blocking film which may include PTFE, TiO2, and carbon black. Onesuch UV blocking film is sold by Saint-Gobain Performance Plastics underthe name CHEMFILM™. Layer Warp Yarn Fill Yarn Matrix Number MaterialMaterial Material Orientation Porosity 1 Fiberglass Fiberglass PTFEOrthogonal Open Mesh 2 Fiberglass Fiberglass PTFE +45° Open Mesh 3Fiberglass Fiberglass PTFE −45° Open Mesh 4 Fiberglass Fiberglass PTFEOrthogonal Open Mesh

[0220] According to this exemplary embodiment, which may be useful for abelt, a multi-layer material 520 (FIG. 6B) includes a first ply 522 withan orthogonal orientation, a second ply 524 with a positive orientation,a third ply 526 with a negative orientation, and a fourth ply with anorthogonal orientation. First ply 522, second ply 524, third ply 526,and fourth ply 528 comprise fiberglass warp and fill yarns woventogether and coated with PTFE. Second ply 524 and third ply 526 have 45degree skew angles. When formed as multi-layer material 520, the warpyarns of first ply 522, second ply 524, third ply 526, and fourth ply528 extend in about the same direction. Plies 522-528 are stitchedtogether using polyester or Kevlar threads.

[0221] Multi-layer material 520 has a first face 550 facing in a firstdirection and a second face 552 facing in a second direction.Multi-layer material 520 is substantially planar. First face 550 isconfigured to carry articles on the belt and second face 552 isconfigured to face opposite the articles. The two skew plies 524, 526are located in the middle of the multi-layer fabric and the orthogonalplies 522, 528 are located towards the faces 550, 552 of the belt. LayerWarp Yarn Fill Yarn Matrix Number Material Material Material Orientation1 Fiberglass Fiberglass Silicone +45° Rubber 2 Fiberglass FiberglassSilicone −45° Rubber 3 Fiberglass Fiberglass Silicone Orthogonal Rubber

[0222] According to this exemplary embodiment, which may be useful foran architectural roof fabric, a multi-layer material 640 (FIG. 7C)includes a first ply 644 with a positive orientation, a second ply 646with a negative orientation, and a third ply 648 with an orthogonalorientation. First ply 644, second ply 646, and third ply 648 comprisefiberglass warp and fill yarns woven together and coated with siliconerubber. First ply 644 and second ply 646 have 45 degree skew angles:When formed as multi-layer material 640, the warp yarns of first ply644, second ply 646, and third ply 648 extend in about the samedirection. Plies 644-648 are stitched together using polyester threads.

[0223] Multi-layer material 640 has a first face 660 extending towardsthe outside environment and a second face 662 facing the interior of thebuilding for which the roof fabric 640 is being used. The two skew plies644, 646 are located towards exterior face 660 and the orthogonal ply648 is located towards interior face 662.

[0224] A protective layer 642 is applied to first ply 644 as a barrierbetween the plies and the environment. Protective layer 642 includes afluoropolymer. Layer Warp Yarn Fill Yarn Matrix Number Material MaterialMaterial Orientation 1 Fiberglass Fiberglass PTFE/FE Orthogonal blend 2Fiberglass Fiberglass PTFE/FE +45° blend 3 Fiberglass Fiberglass PTFE/FE−45° blend

[0225] According to this exemplary embodiment, which may be useful foran expansion joint, a multi-layer material 730 (FIG. 8B) includes afirst ply 740 with an orthogonal orientation, a second ply 742 with apositive orientation, and a third ply 744 with a negative orientation.First ply 740, second ply 742, and third ply 744 fiberglass warp andfill yarns woven together and coated so that the Fluoroelastomer in theblend remains uncured. Second ply 742 and third ply 744 haveorientations of 45 degrees. When formed as multi-layer material 730, thewarp yarns of first ply 740, second ply 742, and third ply 744 extend inabout the same direction. Plies 740-744 are joined together bystitching.

[0226] Multi-layer material 730 has a first face 732 extending towardsthe outside environment and a second face 734 facing the interior of thecylindrical or box-shaped expansion joint 716 (FIG. 8A). The two skewplies 742, 744 are located towards interior face 734 and the orthogonalply 740 is located towards exterior face 732.

[0227] A protective layer 746 is applied to third ply 746 as a barrierbetween the plies and the material to be transported through expansionjoint 716. Protective layer 746 includes PTFE. Property Units ValueWeight oz./sq. yd. 80 ± 3 Thickness inches 0.080 nominal Strip TensileStrength lbs./in. Warp (Dry) 1800 min average Fill (Dry) 1800 minaverage D 1 (Dry) 1800 min average D 2 (Dry) 1800 min average StripTensile Strength lbs./in. After 50 lbs Creasefold Warp (Dry) 1750 minaverage Fill (Dry) 1750 min average D 1 (Dry) 1750 min average D 2 Dry)1750 min average Tear Strength lbs. (Trapezoidal) Warp  700 min averageFill  700 min average Seam Peel Adhesion lbs./in. Dry  20 min averageWet  20 min average Uniaxial Elongation % (at 40 lbs./in.) Warp 2.5 maxaverage Fill 2.0 to 5.5 average Dielectric Constant 2.35 nominal LossTangent 0.006 nominal Water Absorption % Less than 2 Hydrophobic Contactdegrees 90 + nominal Angle Incombustibility seconds 0 to flameoutService Temperature degrees F. −60 to 500

[0228] A radome cover made of a fabric which uses plies havingnon-orthogonally oriented plies according to one example has theabove-listed physical and performance properties. The fabric is amulti-ply fabric where the plies are comprised of PTFE coated Keviar anda film is located on the outer surface of the fabric. The radome isdesigned to be RF transmissive with good performance at multiplefrequencies.

[0229] The exemplary fabric's quadriaxial, multi-ply, laminatedconstruction provides good dimensional stability, even in the mostextreme environments. The composite offers durable hydrophobicity,enhanced flexural characteristics, very high tear strength, and goodhigh temperature/fire performance. Property Units Value Weight oz./sq.yd. 70 ± 3 Thickness inches 0.070 nominal Strip Tensile Strengthlbs./in. Warp (Dry) 1200 min average Fill (Dry) 1200 min average D 1(Dry) 1200 min average D 2 (Dry) 1200 min average Strip Tensile Strengthlbs./in. After 50 lbs Creasefold Warp (Dry) 1150 min average Fill (Dry)1150 min average D 1 (Dry) 1150 min average D 2 Dry) 1150 min averageTear Strength lbs. (Trapezoidal) Warp  500 min average Fill  500 minaverage Seam Peel Adhesion lbs./in. Dry  20 min average Wet  20 minaverage Uniaxial Elongation % (at 40 lbs./in.) Warp 2.5 max average Fill2.5 to 5.5 average Dielectric Constant 2.35 nominal Loss Tangent 0.005nominal Water Absorption % Less than 2 Hydrophobic Contact degrees 90 +nominal Angle Incombustibility seconds 0 to flameout Service Temperaturedegrees F −60 to 500

[0230] A radome cover made of a fabric which uses plies havingnon-orthogonally oriented plies according to one example has theabove-listed physical and performance properties. The fabric is amulti-ply fabric where the plies are comprised of PTFE coated Kevlar anda film is located on the outer surface of the fabric. The radome isdesigned to be RF transmissive with good performance at multiplefrequencies.

[0231] The exemplary fabric's quadriaxial, multi-ply, laminatedconstruction provides good dimensional stability, even in the mostextreme environments. The composite offers durable hydrophobicity,enhanced flexural characteristics, very high tear strength, and goodhigh temperature/fire performance.

Example 11

[0232] A woven fabric with a count of 8×12, warp yarns of 1000 d Kevlarand fill yarns of 3000 denier Kevlar, is dipped at 4 fpm through aSilicone/PTFE formulation at 1.32 sg (43.4% solids). It is then driedand baked for 90 seconds at 300 F and 515 F respectively.

[0233] The yarns of this woven material are subsequently reoriented onequipment depicted in FIG. 4. The payout of this equipment is angled at45 degrees to the web path. All of the other rolls are at 90 degrees tothe web path. Reorientation is done at 3 fpm without adding new coating.

Example 12

[0234] A woven fabric with a count of 8×12, warp yarns of 1000 d Kevlarand fill yarns of 3000 denier Kevlar, is dipped at 4 fpm through aSilicone/PTFE formulation at 1.32 sg (43.4% solids). It is then driedand baked for 90 seconds at 300 F and 515 F respectively.

[0235] The yarns of this woven material are subsequently reoriented onequipment depicted in FIG. 4. The payout is angled at 45 degrees to theweb path. All of the other rolls are at 90 degrees to the web path.Reorientation is done at 3 fpm. While the reorientation is occurring,the fabric is dipped through a PTFE dispersion at 1.50 sg (59.5%solids). It is then dried and baked for 120 seconds at 220 F and 630Frespectively.

[0236] The fabric is given a third coating. 1.50 sg PTFE dispersion(59.5%) is applied at 3 fpm, then dried and baked for 120 seconds at 220F and 630F respectively.

Example 13

[0237] This ply consists of a 26×26 count basket weave using 2000 denierKevlar yarn in both warp and fill. It is coated with a silicone/PTFEformulation at 1.32 sg, 4 fpm, drying and baking for 90 seconds at 300Fand 515F respectively.

Example 14

[0238] The coated fabrics described in examples 11 and 12 are stitchedto the fabric described in example 13. These three plies are arranged inan order of example 13, then example 12, and then example 11 and arestitched together using Kevlar 46 Natural stitching thread (SyntheticFibers) at 4.5 gauge chain stitch with 4.5 to 7.7 stitches per inch.

[0239] The stitched composite is further coated with 42 osy of PTFE.Each PTFE coating pass is dried and baked (2 minutes at 250F and 555Frespectively). The coated fabric is then sintered for 80 seconds at 750Fand then coated with 15 osy of a PTFE/TiO2 formulation and finished witha 2 osy topcoat of FEP dispersion. Each of these passes is dried, bakedand sintered for 120 seconds.

[0240] The properties of this product are: Breaking strength Warp 1317pli Fill 1091 pli Diagonal 1 1093 pli Diagonal 2  759 pli Trap. TearWarp  766 lbs Fill  946 lbs Diagonal 1  733 lbs Diagonal 2  811 lbsCrease Fold Warp 1270 pli Fill 1142 pli Diagonal 1  984 pli Diagonal 2 774 pli Seam Strength Warp 1147 pli Fill 1107 pli Diagonal 1  915 pliDiagonal 2  673 pli

Example 15

[0241] A woven Kevlar fabric with a count of 10×17.5 ypi with 1140Denier Kevlar 49 yarn is reoriented on equipment shown in FIG. 4. Theaccumulator rolls are angled 15 degrees from the cross machine direction(75 degrees from the web path). At about the same time it is coated witha PTFE/PFA formulation containing 5% by weight PFA based on solids. Itis dried and sintered for 90 seconds at 300F and 680F respectively. Thereoriented fabric is dipped through 1.45 sg PTFE two more times, driedand baked for 90 seconds at 300F and 580F respectively after each dip.

Example 16

[0242] Two layers of material made in example 4 are laid up so that thewarp yarns of one ply run parallel to the warp yarns of the other andthe fill yarns are at +30 in one ply and −30 in the other ply. A thirdlayer consisting of cast PTFE film with TiO2 as a UV block placed on oneface and the three layers (film and two fabrics) are laminated togetherusing a B. F. Perkins 100″, 100 Ton, 3 Roll Calendar the 4 fpm with 1750psig hydraulic pressure (≈2000 lbs/in.). The tacked laminate is thensintered for 120 seconds at 750 F.

[0243] The invention has been described with reference to variousspecific and illustrative and exemplary embodiments and techniques.However, it should be understood that many variations and modificationsmay be made while remaining within the spirit and scope of theinvention. Also, while individually coated plies made according to theabove description are particularly useful for forming antenna covers,industrial belts, structural materials, and expansion joints, the pliesmay also be used to advantageously design multi-ply materials intendedfor other uses. Also, while reference has been made in the specificationto a multi-layer material, in each case it is contemplated that themulti-layer material could be a multi-ply fabric where two or more ofthe layers are made of plies of fabric. The description in thisapplication is even more specifically believed to be useful formulti-layer materials that can be classified as multi-ply woven fabricswhere two or more of the plies are formed by a weaving process.

What is claimed is:
 1. A method for forming a composite, the methodcomprising: providing a woven ply comprising a starting orientation;changing the orientation of the ply to a changed orientation; andindividually stabilizing the changed orientation of the ply.
 2. Themethod of claim 1, wherein the changed orientation comprises anon-orthogonal orientation.
 3. The method of claim 2, wherein thechanged orientation comprises a skew angle of about 30 degrees to about60 degrees.
 4. The method of claim 1, wherein the starting orientationis an orthogonal orientation.
 5. The method of claim 1, wherein changingthe orientation of the ply to a changed orientation comprises changingthe orientation of the ply more than once.
 6. The method of claim 5,wherein changing the orientation of the ply more than once compriseschanging the orientation of the ply using both a payout station and anaccumulator.
 7. The method of claim 1, wherein providing a woven plycomprises providing the woven ply to a payout station.
 8. The method ofclaim 1, wherein providing a woven ply comprises weaving the ply.
 9. Themethod of claim 1, wherein individually stabilizing the changedorientation of the ply comprises coating the ply.
 10. The method ofclaim 9, wherein coating the ply comprises dip coating the ply.
 11. Themethod of claim 1, wherein individually stabilizing the changedorientation of the ply comprises laminating the ply.
 12. The method ofclaim 1, further comprising connecting the woven ply to a second wovenply to form a multi-ply material.
 13. The method of claim 12, whereinthe woven ply and the second woven ply have different orientations. 14.The method of claim 12, wherein the woven ply comprises a positivenon-orthogonal orientation and the second woven ply comprises a negativenon-orthogonal orientation.
 15. The method of claim 12, furthercomprising adding a protective film to the multi-ply material.
 16. Themethod of claim 1, further comprising using the individually stabilizedwoven ply to form a flexible composite.
 17. The method of claim 16,wherein the woven ply comprises a non-orthogonal orientation.
 18. Themethod of claim 1, wherein changing the orientation of the ply to thechanged orientation and individually stabilizing the changed orientationof the ply occur at about a same time.
 19. The method of claim 1,wherein individually stabilizing the changed orientation of the plycomprises individually stabilizing the ply using a stabilizing agentcomprising a material selected from a group consisting of a siliconerubber, a urethane rubber, a urethane, a polyurethane, a polyvinylchloride, a polyvinylidene chloride, a polyvinyl alcohol, afluoropolymer, and combinations thereof.
 20. The method of claim 19,wherein the material is a fluoropolymer.
 21. The method of claim 19,wherein the material is PTFE.
 22. The method of claim 19, wherein thematerial is selected from a group consisting of a silicone rubber, aurethane rubber, and combinations thereof.
 23. The method of claim 1,wherein individually stabilizing the changed orientation of the plycomprises individually stabilizing the ply using a stabilizing agentconsisting essentially of a material selected from a group consisting ofa silicone rubber, a urethane rubber, a urethane, a polyurethane, apolyvinyl chloride, a polyvinylidene chloride, a polyvinyl alcohol, anda fluoropolymer.
 24. A method for forming a material having anindividually stabilized ply, the method comprising: providing a plycomprising a non-orthogonal orientation; and coating the ply in itsnon-orthogonal orientation with a matrix material to individuallystabilize the non-orthogonal orientation of the ply.
 25. The method ofclaim 24, further comprising changing an orientation of the ply from astarting orientation to the non-orthogonal orientation.
 26. The methodof claim 25, further comprising pre-coating the ply-prior to changingthe orientation of the ply.
 27. The method of claim 24, furthercomprising at least one of curing and sintering the ply after coatingthe ply.
 28. The method of claim 24, wherein coating the ply comprisesdip coating the ply.
 29. A method for forming a material, comprising:providing a ply comprising a non-orthogonal orientation; and laminatingthe ply in its non-orthogonal orientation to individually stabilize theply.
 30. The method of claim 29, further comprising changing anorientation of the ply from a starting orientation to the non-orthogonalorientation.
 31. The method of claim 30, wherein the startingorientation comprises an orthogonal orientation.
 32. A method forforming a material having an individually stabilized ply, the methodcomprising: weaving a ply; maintaining the woven ply in a non-orthogonalorientation for an extended period before the ply is individuallystabilized with a stabilizing agent; and individually stabilizing theply that has been maintained in its non-orthogonal orientation with astabilizing agent.
 33. The method of claim 32, wherein maintaining thewoven ply comprises maintaining the woven ply using an interleaftechnique.
 34. The method of claim 32, further comprising changing anorientation of the woven ply from a starting orientation to thenon-orthogonal orientation.
 35. The method of claim 33, furthercomprising pre-stabilizing the woven ply with a stabilizing agent priorto changing the orientation of the woven ply.
 36. A method for forming amaterial having an individually stabilized ply, the method comprising:providing a ply of woven material; and individually stabilizing the plyin a non-orthogonal orientation using a stabilizing agent comprising amaterial selected from a group consisting of a silicone rubber, aurethane rubber, a urethane, a polyurethane, a polyvinyl chloride, apolyvinylidene chloride, a polyvinyl alcohol, a fluoropolymer, andcombinations thereof.
 37. The method of claim 36, wherein the materialis a fluoropolymer.
 38. The method of claim 36, wherein individuallystabilizing the ply comprises coating the ply with PTFE.
 39. The methodof claim 36, wherein the material is selected from a group consisting ofa silicone rubber, a urethane rubber, and combinations thereof.
 40. Themethod of claim 36, wherein the woven ply is provided with a firstorientation and the method further comprises changing an orientation ofthe woven ply from a first orientation to the non-orthogonal orientationwhich is stabilized.
 41. The method of claim 36, wherein individuallystabilizing the ply in a non-orthogonal orientation comprisesindividually stabilizing the ply using a stabilizing agent consistingessentially of a material selected from a group consisting of a siliconerubber, a urethane rubber, a urethane, a polyurethane, a polyvinylchloride, a polyvinylidene chloride, a polyvinyl alcohol, and afluoropolymer.
 42. A system for forming an individually stabilized ply,comprising: a payout station configured to provide a woven ply; and ameans for individually stabilizing a non-orthogonal orientation of thewoven fabric ply after the woven ply has been provided by the payoutstation.
 43. The system of claim 42, wherein the means for individuallystabilizing is configured to coat the woven ply.
 44. The system of claim42, wherein the means for individually stabilizing comprises a dip panconfigured to contain a matrix material.
 45. The system of claim 42,wherein the payout station is configured to change an orientation of thewoven ply.
 46. The system of claim 42, further comprising an accumulatorconfigured to change an orientation of the ply.
 47. The system of claim46, wherein the payout station is configured to change an orientation ofthe woven ply.
 48. A system for forming an individually stabilized ply,comprising: a means for altering an orientation of a woven fabric ply;and a means for individually stabilizing the altered orientation of thewoven fabric ply.
 49. A multi-ply composite formed by a method forforming a material having an individually stabilized ply, the multi-plycomposite comprising: a first woven ply comprising a firstnon-orthogonal orientation; and a second ply comprising a secondnon-orthogonal orientation different than the first non-orthogonalorientation, the first non-orthogonal orientation and the secondnon-orthogonal orientations occurring in overlapping areas of themulti-ply composite.
 50. The multi-ply composite of claim 49, whereinthe multi-ply composite consists essentially of two to six plies. 51.The multi-ply composite of claim 49, wherein the first ply comprises apositive non-orthogonal orientation; and the second ply comprises anegative non-orthogonal orientation.
 52. The multi-ply composite ofclaim 51, wherein the second ply is woven and individually stabilized.53. The multi-ply composite of claim 51, wherein the first ply isdirectly connected to the second ply.
 54. The multi-ply composite ofclaim 51, further comprising a third ply comprising an orthogonalorientation.
 55. The multi-ply composite of claim 49, wherein one of thefirst ply and the second ply is individually stabilized by a stabilizingagent comprising a material selected from a group consisting of asilicone rubber, a urethane rubber, a urethane, a polyurethane, apolyvinyl chloride, a polyvinylidene chloride, a polyvinyl alcohol, afluoropolymer, and combinations thereof.
 56. The multi-ply composite ofclaim 49, wherein the first ply is individually stabilized by astabilizing agent comprising a material selected from a group consistingof PTFE, PVC, FEP, and PFA.
 57. The multi-ply composite of claim 49,wherein the first ply comprises a first face and a second face andcomprises a coating over substantially all of the first face and acoating over substantially all of the second face.
 58. The multi-plycomposite of claim 49, wherein a first set of yarns of the first ply arecomprised of a material selected from a group consisting of a glassfiber, a nylon, a polyester, an aramid, a polyethylene, a polyolefin, apolyimide, a carbon fiber, a polybenzimidazole, a polybenzoxazole, afluorocarbon, and mixtures thereof.
 59. The multi-ply composite of claim49, wherein a first set of yarns of the first ply comprise a glassfiber.
 60. The multi-ply composite of claim 49, wherein a first set ofyarns of the first ply comprise an aramid.
 61. The multi-ply compositeof claim 49, wherein a first set of yarns of the first ply are comprisedof a material selected from a group consisting of a nylon and apolyester.
 62. The multi-ply composite of claim 49, further comprising aprotective film.
 63. The multi-ply composite of claim 62, wherein theprotective film comprises a fluoropolymer.
 64. A composite formed by amethod for forming a material having an individually stabilized ply, thecomposite comprising: a woven ply comprising a non-orthogonalorientation; wherein the woven ply is individually stabilized by amatrix material comprising a material selected from a group consistingof a silicone rubber, a urethane rubber, a urethane, a polyurethane, apolyvinyl chloride, a polyvinylidene chloride, a polyvinyl alcohol, afluoropolymer, and combinations thereof.
 65. The composite of claim 64,further comprising a second ply.
 66. The composite of claim 65, whereinthe woven ply comprises a positive non-orthogonal orientation; and thesecond ply comprises a negative non-orthogonal orientation.
 67. Thecomposite of claim 64, wherein one of the first ply and the second plyis individually stabilized by a stabilizing agent comprising a materialselected from a group consisting of PTFE, silicone rubber, PVC, FEP, andPFA.
 68. The composite of claim 64, wherein the woven ply comprises afirst face and a second face and comprises a coating over an entirety ofthe first face and a coating over an entirety of the second face. 69.The composite of claim 64, wherein a first set of yarns of the first plyare comprised of a material selected from a group consisting of a glassfiber, a nylon, a polyester, an aramid, a polyethylene, a polyolefin, apolyimide, a carbon fiber, a polybenzimidazole, a polybenzoxazole, afluorocarbon, and mixtures thereof.
 70. The composite of claim 64,wherein a first set of yarns of the first ply comprise a glass fiber.71. The composite of claim 64, further comprising a protective film. 72.The composite of claim 71, wherein the protective film comprises afluoropolymer.